Vehicle driveline systems employing centrifugally operated friction clutches are well known in the art. A centrifugal clutch typically includes an input member driven by a primer mover, usually an electric motor or internal combustion engine, and weights pivotable or rotatable with respect to the driving member which, upon rotation of the input member, will move radially outwardly under the effect of centrifugal force to cause the input member to frictionally engage an output member. Examples of centrifugally operated clutches may be seen by reference to U.S. Pat. Nos. 3,580,372; 3,580,372; 3,696,901; 5,437,356; 3,810,533; 4,819,779; 5,441,137; 5,730,269 and 4,610,343, the disclosures of which are incorporated herein by reference.
One characteristic of a centrifugal clutch is that the vehicle employing the clutch can be launched without any secondary control other than the primary driver input via the vehicle throttle. However, in vehicles that include a compliant driveline, such as a heavy truck, the driver is required to carefully apply the throttle during launch to avoid over-applying prime mover torque that would induce undesirable torsional oscillations in the driveline. Accordingly, the need exists for a control system that, among other things, provides a smooth, controllable engagement of a centrifugal clutch, regardless of throttle input.